Q: My wife and I each have our own iPhones and iPads and use separate iTunes accounts for them. Although we share iTunes on the same computer, we buy and download stuff under our own IDs and just keep it all in the same library. Recently I decided to subscribe to iTunes Match with my account, thinking that both of our devices could share our music library through iCloud that way. However, it seems that this requires her to sign in on her devices with my account, which it isn’t letting her do—it says something about not being able to switch accounts for 90 days. Oddly, however, it works just fine on her iPad. Any ideas how I can deal with this? Kind of defeats the purpose of subscribing to iTunes Match if we can’t use it on all of our devices.

- Robert

A: Unfortunately, there’s probably nothing you can do except to wait for the 90 day time limit to expire on her iPhone. Presumably as a piracy prevention measure, Apple prevents iOS devices from changing iTunes Store accounts more than once every 90 days when they have been used for iTunes in the Cloud features. These features include re-downloading previously purchased music, videos or iBooks directly on your device, enabling automatic downloads of newly purchased content, and iTunes Match.

It’s likely that you had no problem switching accounts on the iPad simply because your wife has never actually used any of those features on her iPad. Actually purchasing new content from the iTunes Store and re-downloading previously purchased apps does not involve this restriction, nor does simply syncing purchased content on via iTunes.

It also appears that Apple will allow you to switch accounts on a given device once without enforcing the 90-day restriction. However, you will normally see a warning advising you of this restriction as soon as you attempt to access a limited iTunes in the Cloud feature, such as enabling automatic downloads or iTunes Match.

Depending on when the timer started, you may not need to wait the full 90 days—the error message you see on the iPhone should indicate how many days are remaining before you can switch accounts.

You can also find this information for all of the devices associated with a given iTunes Store account by accessing your iTunes Store Account Information via iTunes and looking at the Manage Devices section under iTunes in the Cloud.

This will show the date that each device was first registered as well as the number of days remaining for any device restrictions. Note that removing a device from this list will not reset the 90-day restriction, nor will restoring a device back to factory settings as Apple tracks iTunes Store restrictions based on a unique device identifier that has nothing to do with your current device settings.

You can try contacting iTunes Store customer service and explaining the situation to them and asking if they can clear the restriction based on your recent iTunes Match subscription. Unless they’re willing to help out, however, your only option is to either way out the remaining of the 90-day restriction or buy your wife a new iPhone.